od: support uintmax_t too

od: support uintmax_t too

This has practical effect only on hypothetical platforms where
uintmax_t is wider than unsigned long long int.
* src/od.c (enum size_spec): New constant INTMAX.
(MAX_INTEGRAL_TYPE_WIDTH): Now equals UINTMAX_WIDTH.
(FMT_BYTES_ALLOCATED): Allow for the extra "l" in "%lld".
Also, fix off-by-two error in size calculation.
(width_bytes, integral_type_size): Add entries for uintmax_t.
(print_intmax): New function.
(decode_one_function): Use it.
(ISPEC_TO_FORMAT): New arg Max_fmt. All uses changed.